2005 Traffic Data

VMT Reporting Methodology

The Traffic Monitoring system produces a number of reports of Vehicle Miles Traveled (VMT) on the public roads of Virginia.  There are a number of ways to slice and categorize the VMT data, and TMS has expanded its report library as requests are received. 

The most prominent difference between families of VMT reports is the nature of the jurisdictions upon which the report is based.  Reports that summarize data by jurisdiction use either the maintenance jurisdiction or the physical jurisdiction.  The reports using physical jurisdiction summarize data based on the actual location of the road segments relative to the corporate and county boundary lines.  The reports using maintenance jurisdiction summarize data base on the organization having jurisdiction over the maintenance of the road segments.  Physical jurisdiction reports are often most valuable to users outside of VDOT or users producing data products intended for users outside of VDOT.  Maintenance jurisdiction reports are usually more valuable to users within VDOT who are establishing performance measures or deriving resource allocation values targeted to groups with the responsibility of construction and maintenance of one or more sectors of the VDOT organization.  There are different reasons why a segment of road might be represented in a different jurisdiction name when reporting by maintenance vs. physical jurisdiction.  Federal highways, for example the Blue Ridge Parkway, Skyline Drive, the George Washington Parkway, the Colonial Parkway, and the Dulles Access Road are represented in the Federal (or Other) jurisdiction on Maintenance Jurisdiction reports, but are represented in the county, city, or town in which they physically sit on Physical Jurisdiction reports.  These road segments would be represented in the Toll (or Other) jurisdiction on Maintenance Jurisdiction reports, but are represented in the county, city, or town in which they physically sit on Physical Jurisdiction reports.  The Loudoun County maintenance groups are responsible for the maintenance of portions of US 50 that are physically placed in Fauquier County.  Because of the juxtaposition of many road segments at physical jurisdictional boundary lines, several road segments around the state are maintained by the neighboring jurisdiction's maintenance authorities.  It is the Maintenance Jurisdiction assigned to a road segment that determines which VDOT district has maintenance responsibilities on that segment.  Many Maintenance Jurisdiction reports are subtotaled by VDOT district.  The Physical Jurisdiction in which the road segment sits is not necessarily an indicator of which VDOT district is responsible for maintenance along that segment, so there is no direct relationship between physical jurisdiction values and VDOT district summary values.  Physical Jurisdiction reports are therefore not grouped by VDOT district.

Other categories upon which the VMT reports summarize data include the Federal Functional Class of the highway facilities and the Federal Vehicle Classification.

The primary function of the VMT reports is to provide the daily vehicle miles traveled for specific groups of facilities and vehicle types.  For convenience, the reports also include the centerline road length in miles.  The VMT reports are not the source system of record, nor are they the authority on road length values.  The VMT reports road length values should be equal to the source system of record values, but this cannot be guaranteed. 

Beginning with the re-released 2004 VMT reports, for each report type, a printable pdf and an Excel spreadsheet are available.  The printable pdf report includes columns for each of secondary, primary, and interstate facilities, and a fourth column for the total.  For each facility group, the Daily Vehicle Miles Traveled (DMVT) and the total road length in miles is listed, as well as the percent of the category total for each line is provided.  The spreadsheet allows more flexibility with space and includes the values found on the printable pdf report as well as the percent of the report total represented by the DVMT and road length values for each line.  Reports using the Maintenance Jurisdiction include a two worksheet spreadsheet.  The second worksheet (labeled "Wide") expands the columns the separate the DVMT and road length values by the maintenance authority.  The first Secondary, Primary, and Interstate column groups on this "Wide" worksheet include values only for VDOT maintained facilities.  To the right of the VDOT Secondary, Primary, and Interstate column groups is the County Secondary column group which contains values for Secondary facilities maintained by a county.  To the right of the County column group are an Urban Secondary and Urban Primary column group, then an Other Secondary and Other Primary column group.  The "Wide" worksheet also includes Lane Mile values with the percentage of the column total and the percentage of the report total.

Because the full names of the VMT reports, including the categories upon which the data are summarized are very long, a standard numbering scheme was initiated with the re-release of 2004 VMT reports.  The four digit report id number uses the following scheme:

First of four digits:

A first digit of 1 indicates the report uses the Physical Jurisdiction in which the road segment sits to group the data for summary.

A first digit of 2 indicates the report uses the Maintenance Jurisdiction responsible for maintenance along the road segment to group the data for summary.

A first digit of 0 (a report ID number that is less than 1000) indicates the report does not summarize jurisdiction data.

Second of four digits:

A second digit of 1 indicates the report includes summaries of only VDOT and County maintained facilities.  (Used only with Maintenance Jurisdiction reports).

A second digit of 2 indicates the report includes summaries of all public roads.

Third of four digits:

A third digit of 0 indicates the report does not group on either the functional classification of the facility nor the vehicle class.

A third digit of 1 indicates the report includes subtotals for each federal functional class.

A third digit of 2 indicates the report includes subtotals for each federal vehicle class.

A third digit of 3 indicates the report includes subtotals for each federal functional class and for each federal vehicle class.

Fourth of four digits:

The fourth digit is usually 0.  A fourth digit value other than zero indicates the report uses a custom method of summary to satisfy a specific request.

A fourth digit of 6 indicates the summaries treat data representing towns as if the town were part of the county in which the town is located.

Reports currently available:

 210 VMT by Federal Functional Class

 220 VMT by Federal Vehicle Class

 230 VMT by Federal Functional Class by Federal Vehicle Class

1200 VMT by Physical Jurisdiction

1206 VMT by Physical Jurisdiction, Towns rolled into Counties

1210 VMT by Physical Jurisdiction by Federal Functional Class

1216 VMT by Physical Jurisdiction by Federal Functional Class, Towns rolled into Counties

1220 VMT by Physical Jurisdiction by Federal Vehicle Class

1230 VMT by Physical Jurisdiction by Federal Functional Class by Federal Vehicle Class

2100 VMT by Maintenance Jurisdiction, State and County facilities only

2200 VMT by Maintenance Jurisdiction

2210 VMT by Maintenance Jurisdiction by Federal Functional Class

2220 VMT by Maintenance Jurisdiction by Federal Vehicle Class

2230 VMT by Maintenance Jurisdiction by Federal Functional Class by Federal Vehicle Class

 Additional reports may be developed as needed, when resources are available, and where data are available.

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